The Scarlet Fever
As mentioned above, it is said that Mary Ingalls lost sight after she contracted a fever, more precisely, the Scarlet Fever, as depicted in The Little House.
However, even though the Scarlet Fever plays the villain role in numerous children’s books, the truth is that Mary turned blind because she had an inflammatory condition that attacks the brain called viral meningoencephalitis, according to the journal Pediatrics.
